Previously, various methods for improving print life of organic photoreceptors have been proposed. In particular, JP-A-60-3638 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") discloses an electrophotographic photoreceptor in which a wear-resistant layer is formed on a photoconductive layer to give the function of the wear resistance to this layer, to thereby improve the print life by separating functions. This electrophotographic photoreceptor can be significantly improved in durability by providing a layer in which a finely divided conductive powder is dispersed in a binder resin, but include the following problem. Namely, although the finely divided conductive powder for adjusting a resistance is dispersed, electric charge is accumulated in the binder resin, resulting in the increased residual potential, particularly under the circumstances of low humidity. Furthermore, JP-A-5-45920 discloses an electrophotographic photoreceptor having a protective layer in which a finely divided powder of a fluororesin such as polytetrafluoroethylene is incorporated in an amount of up to about 7% by weight. However, this electrophotographic photoreceptor has the problem that an increase in residual potential is observed, though excellent in durability.
As a countermeasure to prevent an incase in residual potential, JP-B-44-834 (the term "JP-B" as used herein means an "examined Japanese patent publication") and JP-A-3-280068 disclose addition of specific chemical compounds. However, an essential improvement is not attained. Namely, the addition of the specific chemical compounds raises the problem of changes with time, and it is difficult to maintain stability over a long period of time.
Further, binder resins containing graft polymers having silicon atoms at their side chains are described in JP-A-61-189559, etc. In this case, silicon atom-containing branched chain moieties of these binder resins are intended to move to interfaces to give lubricity and mold releasing character, essential properties of silicone, to a surface layer. However, these binder resins does not exhibit good wear resistance.